﻿<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>:empty选择器</title>
    <style type="text/css">
    p{
        width:150px;
        height:30px;
    }
    :empty{background-color: #999;}
    </style>
</head>
<body>
    <p>草树知春不久归，</p>
    <p>百般红紫斗芳菲。</p>
    <p>杨花榆荚无才思，</p>
    <p></p>
    <p>惟解漫天作雪飞。</p>	
</body>
</html>
    
    
    
    
    
    